LM2940 DATASHEET PDF
The LM/LMC positive voltage regulator features the ability to source 1A of output current with a dropout volt- age of typically V and a maximum of. The LM LMC positive voltage regulator features the ability to source 1A of output current with a dropout voltage of typically 0 5V and a maximum of 1V. The LM positive-voltage regulator features the Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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Would something like this work? Sign up using Email and Password. You have 5V on the schematic which can’t work. I have used a ground-plane in my PCB design. If you look at page 18 in its datasheet the ESR for the uF, 6. Now my confusion starts with ESR and capacitor type Have you taken their compulsory advice re the output capacitor?
LM Datasheet(PDF) – National Semiconductor (TI)
Tom Wilson 68 7. What about with a simple resistor load at the same current, does it have the same problem?
They need to be rated above my voltages also. Or offer an alternative regulator that is more linear at high frequency As suggested in this answer?
Is your automotive environment 12V or 24V? My note started from the fact that both regulator are rated at 24V input and capable of 1A, and you didn’t initially specify yours needs.
JohnLincoln God Member Posts: Alas the data on minimum ESR is rather sketchy nothing for “C” case for exampleso you darasheet to guesstimate from just these two graphs or get an ESR meter and measure it, or even just with your scope and a function gen that can hit those Datasehet frequencies where you see oscillation.
In second case the OKI is highly suggested. Less crucial is a picture of the output voltage waveform especially as we don’t know what bad probing techniques you may have used. What is the xatasheet voltage? Whether this is really what they intend is unknown.
National Semiconductor – datasheet pdf
It can be 2x to 4x higher at 2 x mains frequency. Locate as close as possible to the regulator. May be increased without bound to maintain regulation during transients. I’m encountering some instabilities in my regulated voltage supply.
I believe that I have conformed to the guidelines in the datasheet. I was reading it on my break and was in a hurry. Because they don’t list ESR on data sheets or at least the ones I’m looking at.
As, if anything, your ESR may be too high it seems I’d try another cap in parallel. And also separately a resistor in series for belts and braces coverage: Hi Russel, thanks for the feedback. dayasheet
I was using the above to supply 5v to my Atmegap-pu project in my automotive environment for controlling the signal that turns on some lights via Mosfet. Your oscillations are at 18 Mhz where the ESR is hopefully datxsheet low. KevinWhite, the 5V net label represents the lowest measured output from the rectifier circuit.
Anything with that rating or higher is fine. Lj2940 for your time. Sign up or log in Sign up using Google. Russell McMahon k 9 The capacitor you linked to is 22pf, which is only one millionth of the specified value. Schematic of the regulation circuit. Sorry, that was my mistake. The average voltage at the input is around 6. This chip predates big cheap ceramic caps, I think.